1. Field Of The Invention
This invention is related to mud saver valves for saving drilling fluid and, in one aspect, to such a valve installable below a kelly or similar apparatus in a drill string for saving drilling mud in the upper drill string while a new drill pipe connection is made.
2. Description of Related Art
During well drilling operations many joints of drill pipe are added to the drill string by first disconnecting an upper portion of the drill string, then installing a new piece of drill pipe by connecting it to the lower drill string and to the upper drill string. During such a connection procedure ("make-up") or during a similar disconnection procedure (or "break-out"), drilling mud within the upper drill string is lost unless some type of valve apparatus closes off the upper drill string, holding drilling mud therein.
Typical mud saver apparatuses are connected below a kelly and shut off drilling mud flow when mud pumps pumping the mud are turned off. The apparatus opens automatically when the mud pumps are again turned on. U.S. Pat. No. 4,262,693 discloses a kelly valve with a ball valve rotatably mounted in a tubular housing with a plurality of movable sleeves and a gear drive for controlling fluid flow through a kelly. These publications also disclose prior art mud saver apparatuses: "Mud Check (tm) Kelly Valve Cuts Waste of Time, Mud," OIL AND GAS JOURNAL, Feb. 20, 1978; "Drilco Mud-Check (tm) Kelly Valve," Drilco Division of Smith International, Inc.; "Swaco Mud Saver Valve," Swaco Division Dresser Industries, Inc.; "Break It Clean With Aitco's Mud Saver Valve," American International Tool Co., Inc.; "Introducing The Compact A-Z Mud Saver Valve," A-Z International Tool Company; "Kellyguard Bulletin 6601," Hydril Mechanical Products Division, 1981; "Make Dry connections Automatically With The Mud Saver (.TM.)," Arrowhead Continental.